Many networks, such as telecommunications networks and data networks, may be conceptually divided into what is referred to as the core network and the access network. The core network is the central part of a telecommunication network that provides various services to customers who are connected by access networks. Core networks are typically wired or fiber optic networks and make up the structural and functional backbone of the network. Core networks are distinct from public data networks, such as the Internet, although core networks may include gateways by which the core network may communicate with public data networks. Access networks provide the interface between individual users and user equipment (UE) and the core network, and are thus considered to make up the topological periphery of a telecommunications or data network, since the function of the access network is, not surprisingly, to allow a UE to access the core network. Access networks often include a wireless component, such as the cellular phone radio interface for mobile phones, 802.11 variant wireless communication for Wi-Fi access points, and the like.
Mobile devices such as cellular telephones, smart phones, personal digital assistants, etc., may have the capability to communicate over multiple types of wireless networks. For example, a cell phone may be able to communicate over both a cellular network such as an LTE (long term evolution) network and a Wi-Fi or WiMAX network. Thus, at any particular geographical location, a cell phone or other UE may be within the vicinity of multiple access networks that could be used by the UE.
FIG. 1 is a network diagram illustrating a portion of a conventional telecommunications network. Network 100 includes a policy and charging rules function (PCRF) 102 and an access network discovery and selection function (ANDSF) 104.
PCRF 102 encompasses policy control decision and flow based charging control functionalities. PCRF 102 provides network control regarding the QoS and flow based charging towards a gateway, such as a gateway between a core network and an access network. PCRF 102 includes a policy engine 106 making policy decisions in response to policy requests and for providing policy instructions to other nodes in the network. PCRF 102 typically includes a Diameter client and/or server 108 for communicating policy-related messages to other nodes via the Diameter protocol.
ANDSF 104 includes its own policy engine 110 as well as an S14 server 112 for communicating policy-related messages to a user equipment UE 114. ANDSF 104 helps UEs, such as UE 114, discover and select non-3GPP networks by providing information on the following:
(1) Available non-3GPP networks, including trusted networks, such as WiMAX, and untrusted networks, such as Wi-Fi networks, as well as information such as network name, security parameters, etc.
(2) Inter-system mobility policy (3GPP Rel-9), including network selection polices for UEs with a single active network connection, e.g., either 3GPP or Wi-Fi, but not both. Polices can be defined by location, coverage area, date and time, etc.
(3) Inter-system routing policy (3GPP Rel-10), including network selection policies for UE with simultaneous active network connections, e.g., 3GPP and Wi-Fi at the same time. Network selection can be done by session, flow, or service. UEs may use non-seamless access, multiple-access PDN connectivity (MAPCON), or IP flow mobility (IFOM).
ANDSF 104 is typically used for offloading calls or data sessions from a cellular telephone network onto a non-3GPP network such as Wi-Fi or WiMAX.
Network 100 also includes various access networks by which UE 114 may connect to a core network 116. In the embodiment illustrated in FIG. 1, network 100 is connected to a 3GPP access network, such as LTE network 118, a trusted access network, such as WiMAX network 120, an untrusted access network, such as Wi-Fi network 122.
A PDN gateway (PGW) 124 provides connectivity between core network 116 and UE 114 via 3GPP networks such as LTE network 118 and trusted networks such as WiMAX network 120. PGW 124 performs policy enforcement, packet filtering for each user, charging support, lawful interception and packet screening. PGW 124 communicates with LTE network 118 via the S5 interface, and communicates with WiMAX network 120 via the S2a interface. PGW 124 communicates with PCRF 102 via the Gx interface.
An evolved packet data gateway (ePDG) 126 provides secure data transmission between UE 114 and core network 116 over an untrusted non-3GPP access network, such as Wi-Fi network 122. ePDG 126 communicates with Wi-Fi network 122 via the SWn interface. ePDG 126 communicates with PCRF 102 via the Gxb interface. PGW 124 and ePDG 126 may communicate with each other via the S2b interface.
A home subscriber server (HSS) 128 is a repository for subscriber profile information, and may communicate with PCRF 102 using the Sh interface, via LDAP, or via other protocols which support database queries.
An application function (AF) 130 provides services to the network, and may communicate with PCRF 102 via an Rx interface.
In the example shown in FIG. 1, ANDSF 104 is part of a packet data network (PDN) 132, such as the Internet, and supports the S14 interface, with which ANDSF 104 can communicate with UEs, such as UE 114. PGW 124 also connects to PDN 132 via a SGi interface. PDN 132 is also connected to Wi-Fi network 122.
There are disadvantages associated with conventional ANDSFs such as ANDSF 104. While conventional ANDSF 104 can provide UE 114 with information about available access networks 118, 120, and 122, and optionally instruct UE 114 to connect to one of the available networks, conventional ANDSF 104 has no access to information available within core network 116. In particular, although ANDSF 104 may have its own policy engine 110, ANDSF 104 has no connection to PCRF 102 or any other policy and charging function through which it might receive policy information from core network 116, and thus cannot consider core network policy when identifying and/or selecting access networks. Moreover, conventional ANDSF 104 has no access to other core network elements, such as HSS 128, AF 130, gateways 124 and 126, traffic detection functions, and the like. As a result, ANDSF 104 can make only simplistic decisions about call offloading. ANDSF 104 can implement only simple, static policies and cannot implement dynamic policies based on variables such as current network load or unavailability of nodes on the network due to maintenance, for example.
It is desired to have an ANDSF with enhanced capabilities, such as the ability to coordinate with nodes within a core network, such as PCRFs, HSSs, gateways, application functions, and traffic detection functions, to make more intelligent decisions about call offloading. Additionally, an enhanced ANDSF would be uniquely situated to allow communication between a UE and a PCRF in a manner not supported in any current networking standards. Accordingly, in light of these difficulties associated with conventional ANDSF, there exists a need for methods, systems, and computer readable media for access network discovery and selection.